Obviously, getting questions into Canvas was not an important factor when your administration decided to go with Canvas. I hope that they now understand. At my university, if this were to happen, my administration would simply tell me to do what you are finding yourself doing, type them all in by hand.
By now you can sense my own similar frustration with Canvas and other LMSs that do not provide a wide variety of means of getting textbook questions into the LMS. This is at least one reason why I really like Moodle - Moodle can import from many different formats. The odd thing about Canvas is that there seems to be lack of getting questions into it that may be in Blackboard format, a format that has been around for a long time and is still used by many publishing companies.
Just last month, a new version of one of my textbooks came out. I went to get the Faculty Resources. The test bank questions were provided in Blackboard, Angel, and Word format. Yep, no Moodle or Canvas. However, I was able to easily import the Blackboard format right into Moodle. Yep, for 12 chapters with around 75 questions per chapter, this took about 20 minutes and I was done.
(Some administrators think that instructors have all kinds of time available for these chores. It doesn't cost them anything more having you to spend your time doing this, does it?)